A pole, 6 m long, lies along the x-axis with one end at the origin. A rope is attached to the other end (point A), which runs to a point on the wall (point B), given by the coordinates (0,-1,2) in meters. Also at point A, there is a force given by F = 400 i - 200 j + 500 k (in N). Determine the projected component of this force (in N) acting along the rope AB.

Respuesta :

Answer:

The value  is [tex] |P| =  187.4 \ N[/tex]

Explanation:

From the question we are told that

   The length of the first rope is  L  =  6 m

    The first rope lie on the x-axis

   The end point of the first rope is  A  

   Now the vector of  A will be [tex]\vec {OA}=  6i[/tex]

   The point of the second rope on the wall is  B

   The coordinate for the point of the second rope on the wall is  (0,-1,2)

   The vector of B will be  [tex]\vec {OB} =  -j+2k[/tex]

Now the coordinate of rope AB is mathematically represented as

    [tex]\vec {AB} =  \vec{OB} -\vec{OA}[/tex]

=>   [tex]\vec {AB} =  -j+2k -6i[/tex]

=>   [tex]\vec {AB} =  -6i -j+2k [/tex]

Generally the magnitude of the rope AB is mathematically evaluated as

       [tex]|\vec{AB}| = \sqrt{(-6^2) +(-1)^2 + (2)^2}[/tex]

       [tex]|\vec{AB}| = \sqrt{41} \ m [/tex]

Generally the unit vector rope AB is mathematically evaluated as

       [tex]\vec r = \frac{\vec {AB}}{|\vec{AB}|}[/tex]

=>     [tex]\vec r =  \frac{1}{\sqrt{41} } * [-6i -j+ 2k][/tex]

From the question we are told that there is a force acting at point A and the force is  

    [tex]F = 400 i - 200 j + 500 k[/tex]

Generally the projected component of this force (in N) acting along the rope AB is mathematically represented as

         [tex] P =  \vec F \cdot  \vec r[/tex]

=>      [tex]  P  = 400 i - 200 j + 500 k  \ * \  \frac{1}{\sqrt{41} } * [-6i -j+ 2k][/tex]

Note ( i . i = 1  ) , (j . j  = 1) , (k . k  = 1)

So    [tex]P =  \frac{1}{\sqrt{41} } [-400 * 6 + 200 * 1 + 500 *2][/tex]

=>   [tex]P =  -187.4 \ N[/tex]

So the magnitude of the projected component of this force (in N) acting along the rope AB is  

    [tex] |P| =  187.4 \ N[/tex]